Not flintlocks but The Grishaverse novels are roughly the right blend of early industrial war + magic. There's a TV show called Shadow and Bone.
The excellent animated show Arcane is maybe close enough to deserve a shout out.

A few series fit the bill:
The Shadow Campaigns by Django Wexler
Temeraire by Naomi Novik
Mistborn Era 2 by Brandon Sanderson
The Cinder Spires by Jim Butcher.

And also:
Guns of the Dawn by Adrian Tchaikovsky